Refactor Finalclass.cpp to not use strings for tilemaps

Instead, they're all stored in a constant int array.

I made sure The Gravitron still has 30 rows just like Outer Space,
though I don't think it matters.

desktop_version/src/Finalclass.h

@@ -10,7 +10,7 @@
 class finalclass
 {
 public:
-    std::vector<std::string> loadlevel(int rx, int ry);
+    std::vector<int> loadlevel(int rx, int ry);
 
     std::string roomname;
     int coin, rcol;